Sugar Composition and Acid Invertase Activity in Spring Barley Plants in Relation to Adult-Plant Resistance to Powdery Mildew

Publisher Website
Google Scholar
Abstract
Ethanol-soluble sugars and acid invertase in healthy and powdery mildew-infected leaves of the susceptible cultivar Peruvian and the adult-plant-resistant cultivar Asse were quantitatively analyzed. A slight increase in glucose, fructose, and sucrose in infected first leaves of barley plants at the first leaf stage appeared at 2-4 days after infection in both cultivars. During sporulation, glucose and fructose increased more in Peruvian than in Asse. Sucrose, in contrast, accumulated in infected leaves of Asse, showing a large increase at 9 days after inoculation. The amounts of fructose and glucose in infected third leaves at the four-leaf stage increased more in Peruvian than in Asse. However, levels of sucrose in infected leaves were greater in Asse than in Peruvian. Increased levels of glucose and fructose in plants of the two cultivars were closely correlated with increases in acid invertase activity. In noninfected fourth leaves of plants with the lower three leaves infected, the amounts of fructose and glucose declined and the amount of sucrose increased in both cultivars. However, the decline was more marked in Peruvian than Asse, whereas sucrose increased more in Asse. The changes in sugar content and activity of acid invertase in infected first and third leaves of the two cultivars were closely associated with infection intensity of powdery mildew. These results suggest that carbohydrate metabolism is less altered in powdery mildew-infected plants of adult-plant-resistant barley cultivars than in susceptible cultivars.